Moving forward: Sharks are the only fish that can't swim backwards — and if you pull a shark backward by its tail, it will die.

What happens to sharks when they swim backwards?

In the event a shark wishes to tilt backwards, it depends on gravity to fall rearward. Any backward movement by shark lets waters into their gills hence interfering with the respiratory process leading to death.

Is it true that sharks can't stop swimming?

Myth #1: Sharks Must Swim Constantly, or They Die

Some sharks must swim constantly in order to keep oxygen-rich water flowing over their gills, but others are able to pass water through their respiratory system by a pumping motion of their pharynx. This allows them to rest on the sea floor and still breathe.